Municipal wastewater treatment facilities, animal farming facilities, and organic industrial treatment and food processing facilities treat and generate highly polluting, odoriferous organic waste streams. With increasing human population density, such facilities have come under increasing pressure to upgrade, modify, or supplement their treatment processes so as to improve the air quality in and around such facilities and further protect the environment, and human and animal health. A particularly persistent problem addressed by the present invention is the treatment of animal excrement containing high concentrations of microbial substrates (nutrients such as phosphorus, sulfur and particularly nitrogen and other organic biodegradable materials as measured by the total biochemical oxygen demand (BOD) test) which, in typical animal treatment systems, not only pollute surface and subsurface water supplies, but also negatively impact air and soil quality. Further, present treatment alternatives for organic waste streams, such as animal excrement, frequently generate and exacerbate the offensive odors.
Traditionally, animal farming was accomplished on large tracts of land in remote rural areas, with the farmer accepting the offensive odors associated with animal husbandry as a necessary evil. Waste excrement generated from the animal farming was gathered and spread on the farm as fertilizer. The animal waste excrement was allowed to slowly decay in the field and a portion of the unstable nutrients, including phosphorous and nitrogen products, were generally taken up by the growing crop plants. The remainder of the bioavailable or biologically useable nutrients was assimilated by the general environment, usually with no negative ecological impact. When incorporated by plant growth, the nutrients were eventually consumed by the animals for an efficient recycling of nutrients.
Modern high-density animal farming practices, particularly modern feedlot and dairy farming practices, have detrimentally impacted the ecological balance of traditional animal farming methods. Modern agricultural practices concentrate larger numbers of animals in ever-smaller areas leaving larger amounts of waste excrement to be managed by distribution to ever decreasing land areas. In addition, the larger amounts of food required by the increasing density of animals per acre and modern intense feeding practices which use supplemental animal feed containing high concentrations of nutrients, result in larger volumes of manure which cannot be efficiently distributed by traditional methods without severe environmental impacts. Fields on which such manures have been spread become exceedingly rich in unstabilized nutrients and sludge, thereby creating a pollution hazard to water bodies and promoting emissions of repugnant odors. Rain, snow and the like falling on the soil, carry large masses of the unstabilized waste (along with accompanying odors) into the underlying soil that may then infiltrate to the underlying groundwater. The runoff created carries the substances to surface water bodies and generates airborne odors. With the flow of water through drainage ditches, groundwater movement and the like, eventually fresh water aquifers, groundwater, surface waters and other water resources become polluted.
The problem of air and water pollution caused by excessive organic wastes can be exacerbated by an accompanying concentration of toxic materials. Concentrations of toxic materials, which may have been used as animal pharmaceuticals, insecticides, and/or herbicides, including heavy metals and the like, may be part of the animal food intake. Though not generally harmful to the animal or the animal product being produced these materials may end up being further concentrated in the animal's excrement, which is in turn discharged to the local ecosystem.
Various solutions have been proposed to solve the waste management problems posed by modern animal farming, but have been judged to be incomplete, too expensive or so specialized that they only serve to change or postpone the problem.
For example, it has been proposed that complex mechanical systems be installed to provide manageable manure slurries and that systems be installed by the farmer to enable spraying the manure slurry on differing land areas in a rotating manner to reduce the impact of excrement concentration. It has also been proposed to isolate manure in depositories secure from rainwater run-off until the stabilization (decaying) process has produced a concentrated, desirable humus material that can then be commercially sold or otherwise distributed to non impacted localities. Such solutions merely allow for the natural incomplete decay of the manure as evidenced by exacerbated odor problems, require constant manpower, do not resolve the problem of migration of unstabilized waste, and require excessive amounts of time, space and money for treatment.
Conventional biological wastewater treatment technologies for domestic, industrial and animal organic wastes utilize aerobic or anaerobic bioconversion processes, with aerobic processes being the most common. Some modern treatment technologies, such as waste stabilization ponds, utilize both aerobic and anaerobic processes wherein different zones are created within a single treatment unit for each different type of microbial bioconversion. Within these systems, the aerobic zone is typically separated from the anaerobic zone by a facultative zone. Facultative zones contain bacteria that can grow and function both in the presence and absence of oxygen.
One generally successful treatment process of the prior art developed by Bion Technologies, Inc., generally known as the BION® NMS process, is a bioconversion process which transforms animal waste excrement, containing significant concentrations of total BOD and nutrients, into an ecologically stable, nutrient rich organic humus material known as BIONSOIL®. As described in U.S. Pat. No. 5,755,852, the BION® NMS process generally includes an anaerobic process in a first zone (an ecoreactor) which utilizes both anaerobic and facultative bacteria and a combination aerobic/anaerobic process which utilize aerobic, anaerobic and facultative bacteria in a second zone (a bioreactor). Alternatively, the BION® NMS process could also include a third zone (a polishing ecoreactor) wherein plants and microorganisms treat the waste.
Generally, the BION® NMS process utilizes a combination of chemical precipitation, physical settling, and natural living systems such as microbes and plants to achieve bioconversion of the waste. Specific treatment systems incorporating the BION® NMS process such as for dairy farms and hog farms are individually designed according to actual conditions but generally include one or more of the three zones; a solids ecoreactor, a bioreactor and a polishing ecoreactor.
As described in U.S. Pat. No. 5,755,852, an ecoreactor is a multi-cell composting, solids dewatering and bioconversion means. A solids ecoreactor of the BION® NMS process requires construction of a plurality of holding cells, surrounded by containment berms, generally arranged so that individual or sets of cells may be periodically taken off-line from the on-going process so that their contents may be harvested (removal of bioconverted biosolids), dewatered (physical unit process, usually mechanical, for reducing moisture content) and/or dried (reduction of water content by vaporizing water to the air) to produce a bioconverted organic humus or BIONSOIL®. Once harvested, the cell(s) are available and are eventually reactivated or placed back on-line within the bioconversion process. The principle function of a solids ecoreactor is to convert excess biomass produced by the bioreactor to an ecologically beneficial humus material.
As described in U.S. Pat. No. 5,755,852, a bioreactor is an organism growth managing, enhancing and concentrating means. The principle function of a bioreactor, which receives oxygen from the atmosphere and/or from direct, mechanically assisted, aeration, is to promote the growth of biological organisms, which utilize both the incoming soluble materials and waste stream solids converted or hydrolyzed to further the bioconversion process. A bioreactor generally comprises a suitably sized pond environment or the like. Although the bioreactor may include some aeration, multiple subenvironments exist within it which utilize aerobic, facultative and/or anaerobic bacteria. The solids ecoreactor, on the other hand, principally contains and utilizes anaerobic and facultative bacterial populations in the flowing liquid phase using the oxygen input in the bioreactor. As bacterial and other organic solids separate from the flowing liquid in the solids ecoreactor, the high solids concentration subenvironments formed contain some active facultative organisms but are predominated by anaerobic microbial populations.
A polishing ecoreactor generally comprises a flooded vegetative complex made up of plants and microorganisms. The plants and microorganisms in the polishing ecoreactor generally capture the nutrients contained in the effluent discharged from a bioreactor. Generally, the water effluent from a polishing ecoreactor is sufficiently pollutant free to allow discharge thereof into a natural receiving water or wetland. Alternatively, this clean discharge may be recycled for beneficial animal husbandry use or used for irrigation.
In the BION® NMS treatment process, wash and flushing water containing slurried animal excrement, and wasted feed, bedding and drinking water from an animal confining barn, penning area or the like, is directed to either or both a solids ecoreactor and a bioreactor. In the solids ecoreactor, non-soluble settleable and floatable solids separate and the bioconversion of the substrate begins. In the bioreactor, microorganisms are enhanced, modified and/or concentrated providing additional bioconversion.
The beneficial humus material produced by the BION® NMS process is substantially free of the objectionable odors normally associated with the animal excrement such as ammonia, hydrogen sulfide, skatole, mercaptans and other odor causing compounds. However, a significant environmental problem which is occasionally associated with the BION® NMS process, and which is usually associated with other present and past wastewater treatment processes, is odor emission from the treatment tanks, cells, or units during the treatment process. Moreover, as is the case for the BION® NMS process, this odor problem can be exacerbated when treatment processes include aeration or intense agitation or mixing which creates greater dispersion, and possibly greater volumes of odorous emissions.
Presently, treatment facilities have two options for coping with these unwanted odors. Either endure the unpleasant odors or manage them. Under the first option, where possible, treatment facilities locate open tanks or treatment process units such as aeration tanks, biological contact tanks, aeration lagoons, and the like in open fields removed from developed areas. This provides for dispersion and dilution of the odors before odor nuisance becomes problematic. Such is the case for typical animal farming treatment processes.
When a treatment facility is located near developed areas another type of passive method for coping with unwanted odors commonly used for wastewater treatment facilities in most locations is the use of buffer zones. As an example, New York City Department of Environmental Conservation suggests minimum buffer distances from developed areas (actual distances depend upon site-specific circumstances), for many treatment process units. The suggested buffer distance from an aerated lagoon is 1,000 feet. Metcalf & Eddy Inc., revised by George Tchobanoglous and Frank Burton, Wastewater Engineering Treatment, Disposal, and Reuse, 3rd Edition 513 (1991). Although these passive techniques could be effective methods for minimizing the effects of odors on developed areas, it is more often the case that the desired distance between the treatment facility and the developed area is unavailable.
Even if the land is available to create a buffer zone, the use of buffer zones is often ineffective. Most importantly, the odors in and around the treatment tanks, vessels or the like are a nuisance, and at times a safety concern, for workers at the facilities.
The second option for treatment facilities is to manage the odors. Odor management techniques include of physical, chemical and biological processes or combinations thereof. Chemical treatment typically includes oxidizing the odor compounds with chlorine, ozone, hydrogen peroxide, or potassium permanganate or using a masking agent to disguise the odor. Physical treatment, probably the most common method, includes containment of the treatment units with covers, collection hoods and air handling equipment, followed by some form of physical treatment which could include combustion, scrubbing, and/or adsorption (with activated carbon). Biological processes include bioconversion of the odor causing compounds by some form of microorganism. Such processes include treatment of odorous air by passing it through activated-sludge aeration tanks, treatment such as disclosed in U.S. Pat. No. 6,087,159, relating to a bio-scrubber which is a cylindrical tower with a high surface area media (usually plastic) on which biological growths are maintained, or as disclosed in U.S. Pat. No. 6,068,774 relating to the addition of biological organisms such as Pseudomonas species to assimilate odor causing compounds.
While such odor treatment methodologies can be effective in treating odors they carry significant disadvantages. For example, they consume considerable amounts of energy to power additional equipment, require significant amounts of capital, often require additional real estate which is usually unavailable and scarce around facilities, and require excessive, continuous maintenance and manpower to keep them running once installed. Further, some such systems consume substantial amounts of costly chemicals or activated carbon which must be regenerated or disposed of.
Applicants have surprisingly discovered a process for the biological conversion of animal waste. This process operates at low dissolved oxygen concentrations throughout the process while maintaining high quantities of diverse populations of microorganisms. The wastewater and sludge are treated simultaneously. Thus, the present invention addresses many of the problems associated with municipal, domestic, industrial, food industry, animal husbandry and other organic wastes, by providing an attractive and efficient means to resolve ecological problems associated with the treatment of organic wastes. More specifically, the present invention addresses the odor emission problem through the efficient, substantially odorless, bioconversion of waste excrement materials or a vast array of other organic wastes into stable, economically and/or ecologically beneficial materials.
Thus, it is an object of the invention to provide an ecologically suitable means for managing organic wastes.
It is another object to provide an improved process for the efficient, substantially odorless, biological transformation of animal wastes, toxins or other organic waste materials economically into suitable materials for recycling to the environment.
It is a further object of the present invention to provide a process to create a biologically active, ecologically beneficial, substantially odorless humus material through the bioconversion of organic waste, particularly animal excrement It is a still further object of the present invention to provide a process to create a biologically active, and/or a nutrient-rich, organic soil.
It is yet another object of the present invention to provide an efficient process that permits biological treatment of higher waste loads in existing treatment facilities and allows for reduced size facilities.
These and other objects will be apparent from the following description of the invention.